scholarly journals Mitigation of Circulating Currents for Parallel Connected Sources in a Standalone DC Microgrid

2021 ◽  
Vol 12 (1) ◽  
pp. 31
Author(s):  
Muhammad Rashad ◽  
Uzair Raoof ◽  
Nazam Siddique ◽  
Daud Mustafa Minhas
Keyword(s):  
Sliding Mode ◽  
Voltage Regulation ◽  
Safe Operation ◽  
Dc Microgrid ◽  
Steady State Condition ◽  
Current Sharing ◽  
Simulation Results ◽  
Parallel Configuration ◽  
Fail Safe ◽  
Circulating Currents

In a standalone DC microgrid, sources are interconnected in a parallel configuration. When sources of different power ratings are parallel connected, there arises a major issue of circulating currents which disturb current sharing by sources as per their capacity. Consequently, the voltage regulation becomes poorer. Additionally, connecting line resistances also play their part to contribute to abnormal current sharing. Droop controllers are normally preferred for the mitigation of circulating currents among parallel-connected sources. However, droop controllers cannot eliminate circulating currents for different rating sources. Hence, current sharing and voltage regulation cannot be ensured simultaneously. To address the issues, a distributed architecture-based Sliding Mode Control (SMC) technique is proposed in this paper. An analysis of the circulating currents for a two-source system is presented. Simulation results are presented to show the effectiveness and fail-safe operation of the proposed technique in a steady-state condition.

scholarly journals A New Control Strategy for Bi-directional DC/DC Converter in DC Microgrid

2021 ◽  
Vol 233 ◽  
pp. 01051
Author(s):  
Tianze Miao ◽  
Xiaona Liu ◽  
Siyuan Liu ◽  
Lihua Wang
Keyword(s):  
Steady State ◽  
Control Strategy ◽  
Feedback Linearization ◽  
Sliding Mode ◽  
Response Speed ◽  
Fast Response ◽  
Sliding Mode Controller ◽  
Exponential Approximation ◽  
Dc Microgrid ◽  
Simulation Results

The bi-directional DC / DC converter in DC microgrid is a typical nonlinear system which has large voltage disturbance during lead accumulator charging and discharging. In order to solve the problem of voltage disturbance, the linearization of the converter is realized by exact feedback linearization, and the sliding mode controller is designed by using exponential approximation law. The simulation results show that the method has fast response speed, strong anti-interference ability and good steady-state characteristics.

scholarly journals The Hierarchical Control Algorithm for DC Microgrid Based on the Improved Droop Control of Fuzzy Logic

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2995 ◽  
Author(s):  
Liang Zhang ◽  
Kang Chen ◽  
Shengbin Chi ◽  
Ling Lyu ◽  
Guowei Cai
Keyword(s):  
Fuzzy Logic ◽  
Control Algorithm ◽  
Voltage Drop ◽  
Hierarchical Control ◽  
Voltage Regulation ◽  
Droop Control ◽  
Dc Microgrid ◽  
Current Sharing ◽  
The Difference ◽  
Bus Voltage

In the direct current (DC) microgrid composed of multiple distributed generations, due to the different distances between various converters and the DC bus in the system, the difference of the line resistance will reduce the current sharing accuracy of the system. The droop control was widely used in the operation control of the DC microgrid. It was necessary to select a large droop coefficient to improve the current sharing accuracy, but a too large droop coefficient will lead to a serious bus voltage drop and affect the power quality. In view of the contradiction between the voltage regulation and load current sharing in the traditional droop control, a hierarchical control algorithm based on the improved droop control of the fuzzy logic was proposed in this paper. By improving the droop curve, the problems of voltage regulation and current sharing were solved simultaneously. The effectiveness of the algorithm was verified by simulation.

scholarly journals Equivalent Sliding Mode Controller for Stability of DC Microgrid

2021 ◽  
Vol 12 (1) ◽  
pp. 23
Author(s):  
Muhammad Rashad ◽  
Uzair Raoof ◽  
Nazam Siddique ◽  
Bilal Ashfaq Ahmed
Keyword(s):  
Reactive Power ◽  
Sliding Mode ◽  
Voltage Regulation ◽  
Pi Controller ◽  
Operating Conditions ◽  
Dc Microgrid ◽  
Dc Microgrids ◽  
Central Controller ◽  
The Stability ◽  
Decentralized Architecture

DC microgrids are gaining popularity due to their lack of reactive power compensation, frequency synchronization, and skin effect problems. However, DC microgrids are not exempted from stability issues. The stability of DC microgrids based on decentralized architecture is presented in this paper. Centralized architecture can degrade system performance and reliability due to the failure of a single central controller. Droop with proportional integral (PI) controller based on decentralized architecture is being used for DC microgrid stability. However, droop control requires a tradeoff between voltage regulation and droop gain. Further, global stability through PI controller cannot be verified and controller parameters cannot be optimized with different operating conditions. To address limitations, an equivalent sliding mode (SM) controller is proposed for a DC microgrid system in this paper. Detailed simulations are carried out, and results are presented, which show the effectiveness of an equivalent SM controller.

Autonomous Voltage Regulation and Current Sharing in Islanded Multi-Inverter DC Microgrid

2018 ◽  
Vol 9 (6) ◽  
pp. 6429-6437 ◽  
Author(s):  
Qiang Yang ◽  
Le Jiang ◽  
Hailin Zhao ◽  
Hongmei Zeng
Keyword(s):  
Voltage Regulation ◽  
Dc Microgrid ◽  
Current Sharing

scholarly journals Compromised Controller Design for Current Sharing and Voltage Regulation in DC Microgrid

2019 ◽  
Vol 34 (8) ◽  
pp. 8045-8061 ◽  
Author(s):  
Renke Han ◽  
Haojie Wang ◽  
Zheming Jin ◽  
Lexuan Meng ◽  
Josep M. Guerrero
Keyword(s):  
Controller Design ◽  
Voltage Regulation ◽  
Dc Microgrid ◽  
Current Sharing

scholarly journals Barrier Function Based Adaptive Sliding Mode Controller for a Hybrid AC/DC Microgrid Involving Multiple Renewables

2021 ◽  
Vol 11 (18) ◽  
pp. 8672
Author(s):  
Ammar Armghan ◽  
Mudasser Hassan ◽  
Hammad Armghan ◽  
Ming Yang ◽  
Fayadh Alenezi ◽  
...  
Keyword(s):  
Barrier Function ◽  
Sliding Mode ◽  
Renewable Energy Sources ◽  
Energy System ◽  
Voltage Regulation ◽  
Sliding Mode Controller ◽  
Dc Microgrid ◽  
Adaptive Sliding Mode ◽  
Adaptive Sliding Mode Controller ◽  
Bus Voltage

Conventional electricity generation methods are under the major revolution, and microgrids established on renewable energy sources are playing a vital role in this power generation transformation. This study proposes a hybrid AC/DC microgrid with a barrier function-based adaptive sliding mode controller, in which 8 kW wind energy system and 4.5 kW photovoltaic energy system perform as the hybrid RESs, and 33 Ah of battery works as the energy storage system. Barrier function-based adaptive sliding mode controller ensures the convergence of the system’s output variable independent of the knowledge of the upper bound of the disturbances. Firstly, global mathematical modeling of the suggested system is ensured. Then, the control laws are defined, providing the DC bus voltage regulation during islanding mode and AC/DC link bus voltage regulation during the grid-connected mode. The proposed barrier function-based adaptive sliding mode controller technique is analyzed through 20 s simulations on MATLAB/Simulink, which validates the controller’s robustness and effectiveness. Furthermore, a comparison of the proposed controller is made with the proportional integral derivative controller, Lyapunov controller, and sliding mode controller. In the end, hardware-in-loop tests are performed using C2000 Delfino MCU F28379D LaunchPad, showing the proposed structure’s real-time performance.

scholarly journals Adaptive Voltage Regulation Control Strategy in a Stand-Alone Islanded DC Microgrid based on distributed Wind / Photovoltaic / Diesel / Energy Storage Hybrid Energy Conversion System

2021 ◽  
Vol 5 (4) ◽  
pp. 26-33
Author(s):  
Adel Elgammal ◽  
Tagore Ramlal
Keyword(s):  
Intelligent Control ◽  
Reactive Power ◽  
Sliding Mode ◽  
Voltage Regulation ◽  
Sliding Mode Controller ◽  
Voltage Profile ◽  
Dc Microgrid ◽  
Hybrid Energy ◽  
Power Adjustment ◽  
Energy Conversion System

An adaptive approach for optimal tuning of a SMC for an automated voltage regulator system is displayed in this study. The approach is centered on hybrid of the GA and MOPSA. In addition, unique objective functions for the controller's parameter optimization are suggested. The performance of the resulting perfect sliding mode controller is confirmed by comparing it to controllers adjusted using various techniques that have been published in the literature. The simulation outcomes indicate that controllers tuned with the projected MOPSO and GA algorithms outperform controllers tuned with existing methods. In addition, a comparison study is performed to select the best controller for use in AVR systems. The suggested algorithm's major benefit is a considerable boost in convergence speed. With step changes and step load modifications in input wind power, the system model with built-in intelligent controller is generated in MATLAB/SIMULINK. The benefits of the recommended intelligent control algorithm are confirmed by comparing the outcomes of the sliding mode controller and the projected MOPSO self-tuned controller. The findings show that the hybrid Wind/PV system's reactive power adjustment capabilities. When used in conjunction with BES, it is extremely successful in optimising the voltage profile although providing active energy to local load.

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